There are known pumps comprising several pumping chambers each formed of a cylinder and a piston or diaphragm moving in the bore of this cylinder. In some pumps, the cylinders are affixed to the frame in what is termed an "axial piston" arrangement, the pistons being displaced along the generating lines of an imaginary cylinder. These pistons are solid with rods which are articulated to connecting rods themselves articulated to a plate inclined with respect to the longitudinal axis of the pump. The inclined plate is moved with a nutational movement by a driving mechanism.
The flow of the liquid, upstream and downstream of each pumping chamber, is controlled by valves assuring a single-acting operation. An intake valve is positioned upstream of a pumping chamber so as to open under the effect of the lowering of pressure created by the induction stroke of the piston. A delivery valve is positioned downstream of each pumping chamber so as to open on the delivery stroke of the piston, the intake valve then being closed.
The liquid-pumping chambers are connected to a common intake pipe via conduit, the flow of the liquid being controlled by the intake valves. The pumping chambers are also connected by conduits to a common delivery pipe, the flow of the liquid being controlled by the delivery valves.
It is necessary to remove the lines previously mentioned when the valves and valve seatings have to be changed. These elements have a relatively short life and it must be possible to replace them rapidly and easily.
The object of the present invention is to limit the disadvantages associated, in known pumps, with the conduits which serve to convey the liquid to the pumping chambers and from these chambers to the common exhaust pipe. The object of the invention is a pump of the axial piston type in which the use of conduits, upstream and downstream of the pumping chambers, for conveying the liquid to be displaced is avoided. The liquid to be displaced is conveyed to short passages, between the general intake line and the chambers and between these chambers and the general delivery line. This results in an equal distribution of the liquid to be displaced in the passages, and in some cases allows the charging pump to be omitted. The risks of cavitation, due to fluctuations in pressure, can also be reduced. Maintenance is easy, thanks to the use of easily removed cylinder heads through which run passages conveying the liquid to be displaced, and which are equipped with valves. The pump according to the invention takes up less space than those known in the art.